Verification of the influence of various shear histories on the strength properties of sandy soils using energetic indices

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K23545
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0303:Civil engineering, social systems engineering, safety engineering, disaster prevention engineering, and related fields
• Research Institution: Public Works Research Institute (2020-2021); National Institute of Maritime, Port and Aviation Technology (2019)
• Principal Investigator: Aoyagi Yudai 国立研究開発法人土木研究所, 土木研究所(つくば中央研究所), 研究員 (40845658)
• Project Period (FY): 2019-08-30 – 2022-03-31
• Keywords: 液状化 / せん断履歴 / 応力-ひずみ関係 / 正規化エネルギー / 室内土質試験 / 再液状化

Outline of Final Research Achievements

There is a social need for highly accurate prediction and determination of "re-liquefaction risk" at locations where liquefaction has occurred in the past. However, current liquefaction determination methods do not take into account the effects of past seismic motion and liquefaction history. This study experimentally verifies the effect of various shear histories on the re-liquefaction strength of specimens. The experimental results are quantitatively analyzed using a newly proposed "energetic index (normalized energy) normalized by the average effective principal stress that changes from moment to moment during the liquefaction process," and an estimation of the strength increase rate during re-liquefaction is attempted from the energetic index.

Free Research Field

地盤工学

Academic Significance and Societal Importance of the Research Achievements

本研究は、過去のせん断履歴・液状化履歴の影響を定量的に表現可能な「エネルギー的指標」を用いて、液状化には至らないようなせん断履歴を与えた際の強度増加率の推定を試みるものである。過去の液状化履歴(再液状化)や過去の地震動によるせん断履歴を、新たに提案している「正規化エネルギー」を用いて定量的に分析することで、過去の様々な履歴を定量的に評価できる可能性があることを示した。これらの研究成果は、地震動による履歴の定量的な評価だけでなく、せん断履歴を活用した新たな液状化試験方法の開発や、せん断履歴を考慮した効率的な施工方法にも繋がるものである。